Yemen said on Wednesday it had arrested a militant cell that had been planning to kidnap the United Arab Emirates' charge d'affaires, after a string of abductions that have targeted Westerners and diplomats in the country.

Interior Ministry spokesman Major-General Mohammed Al Qaidy said security forces arrested the six members of what it called a terrorist cell a month ago, and found weapons, fake passports and fake Yemeni currency in their possession.

"The gang members confessed that they were going to receive a reward of 5 million riyals ($1.33m) and a four-wheel drive car if they managed to kidnap the UAE's charge d'affaires," Qaidy told a news conference.

It was not immediately clear who had promised the ransom but kidnapping is common in Yemen. It is sometimes carried out by militants specifically targeting Westerners but is also used as a tactic by tribesmen to resolve disputes with the government, and by opportunists hoping to sell hostages on to other groups.

Home to Al Qaeda in the Arabian Peninsula, southern separatists and rebels in the north, the US-allied country, which shares a long border with oil-exporting heavyweight Saudi Arabia, is struggling to impose security across its territory.

The army on Tuesday launched a major offensive to root out Al Qaeda militants in two southern strongholds, following air strikes earlier this month that Yemen said targeted the militants and killed some 65 of them in central and southern parts of Yemen.

Qaidy said security forces also arrested another three-person cell that had made threats against the Saudi embassy.

A Saudi diplomat taken hostage in the southern port city of Aden in 2012 is still missing.

In the weeks between March 1 and April 23, 148 people were killed by "terrorist acts", including army and security forces, citizens and social personalities, Qaidy said.

Separately, a Yemeni military source said that three Al Qaeda militants were killed and dozens wounded in the offensive taking place in the southern Mahfad region of Abyan province.

The insurgents have posed a major challenge to government efforts, carrying out dozens of bombings, suicide attacks and commando-style raids against military installations, government facilities and foreign nationals, killing hundreds of people since 2012.